Whirley balls amusement device

Abstract

A hand held housing can be manipulated to cause a pair of balls to move in opposite directions along a groove in the housing. The groove has upstanding inner and outer walls. These walls have a rough surface and the balls have a snug fit in the groove.

I claim: 
     
       1. An amusement device comprising a plastic cylindrical housing having a horizontally disposed upwardly facing circular groove in its bottom wall, said groove being defined on its outer periphery by a vertical wall substantially higher than the depth of the groove, said groove being defined by a rough surface on inner and outer walls of said groove, at least two marble balls in said groove, said balls being of the same mass and having different colors, said balls having a snug fit in said groove and substantially simultaneously contacting said surface of both said walls, said housing being of a size so that it can be hand-held and manipulated to cause the balls to move in opposite directions, and said inner wall having a sufficient height to prevent movement of the balls radially inwardly during normal use. 
     
     
       2. A device in accordance with claim 1 wherein said housing has an inwardly extending lip at the upper end of said vertical wall. 
     
     
       3. A device in accordance with claim 1 wherein said bottom wall has its periphery connected to the upper end of the inner periphery of said groove and has a centrally disposed hole coaxial with the upper end of said housing. 
     
     
       4. A device for demonstrating the principal of conservation of momentum comprising a housing having an open top and a horizontally disposed upwardly facing circular groove, said groove being defined on its outer periphery by a vertical wall substantially higher than the depth of the groove, said groove defined by a rough surface on inner and outer walls of said groove, at least two balls of hard material in said groove, said balls being of equal mass, said balls having snug fit in said groove and substantially simultaneously contacting said rough surface on both the inner and outer walls of said groove, said housing being of a size so that it can be hand-held and manipulated to cause the balls to move in opposite directions in said groove and contact one another, and said inner wall having a sufficient height to prevent movement of the balls radially inwardly during normal use. 
     
     
       5. A device in accordance with claim 4 wherein said housing has an inwardly extending lip at the upper end of said vertical wall. 
     
     
       6. A device in accordance with claim 4 wherein the housing has a bottom wall containing a centrally disposed hole therein coaxial with the upper end of said housing. 
     
     
       7. A device in accordance with claim 4 wherein said balls are made of glass. 
     
     
       8. A device in accordance with claim 4 wherein said balls are made of steel. 
     
     
       9. A device in accordance with claim 4 wherein the elevation of the upper end of the inner wall of the groove is approximately at the center of the balls. 
     
     
       10. A device in accordance with claim 9 wherein said balls are of different colors.